1. Field of the Invention
The invention relates to the fields of flow detection, measurement and control. The invention also relates to fire suppression systems, and, in particular, to multi-purpose piping systems for fire protection in structures and flow elements related thereto.
2. Description of the Prior Art
Practically any system where fluid flows in a conduit can use flow measurement devices. There are any many different kinds of flow measurement devices as there are systems where fluids flow in a conduit (such as a typical round pipe). For example, it is well known that there is a pressure drop across an orifice plate, and that this pressure drop can be used to determine the fluid flow through the pipe. The pressure drop is proportional to the velocity of the fluid in the pipe. As another example, a positive displacement device may be placed in a conduit, which directly measures the volume of fluid flowing therethrough. From the known volume measured by the positive displacement device, the velocity of the fluid in the pipe can be determined. Each type of flow measurement device has its strengths and weaknesses, and may be applicable to one system, while not being suitable for another.
Check valves (single and double acting) are also widely used in systems where fluids flow in conduits. The purpose of a check valve is to allow flow in one desired direction, but prevent flow in the opposite undesired direction. Existing check valves often use a moving seat, which is forced open by fluid flowing in the desired direction, but which moving seat is sealingly forced against an annular shoulder, preventing flow in the undesired, opposite direction.
It is well known to use electronic sensor means to transmit a signal generated by a flow measurement device to a read out or alarm means. The electronic output may be generated in response to a pressure transducer or the like. There are a myriad of ways to generate an electronic signal proportional to flow of a fluid in a conduit. As with our orifice plate noted above, the differential pressure is proportional to the flow in the conduit. Therefore, a differential pressure transducer exposed to the up stream and down stream fluids would produce an output electrical signal proportional to the flow of fluid through the conduit. In one type of paddle flow switch, the volume between the paddles is known, and a signal is generated indicating the number of revolutions per unit time of the paddle, thus allowing calculation of the flow velocity. Vane-type paddle flow switches are typically used in the fire protection industry, but vane-type paddle flow switches are generally not capable of measuring flow with any degree of accuracy.
Gems® Sensors markets several types of flow switches in their catalogues, which switches use Reed switch technology to measure flow. These devices are equipped with a magnet which is displaced by liquid flow to actuate a hermetically-sealed Reed switch isolated within the unit body of the switch. A positive spring-return de-actuates the switch when flow decreases. The pressure drop is low since the flow sensing elements moves out of the flow path after switch actuation. With only one moving part—the shuttle, paddle, or piston—Gems Sensors' flow switches are alleged to be inherently reliable. There are no bellows, diaphragms, or mechanical linkages to wear or get out of adjustment. Gems Sensors' FS-200 incorporates a magnet-equipped shuttle, which is displaced by fluid flow, actuating the hermetically sealed Reed switch. Gems Sensors also provides options vane bypass, which can be opened to allow additional flow to pass through the sensor before the Reed switch is activated. This optional vane device is externally adjustable with a blade screwdriver, for simple adjustment of the amount of flow required to actuate the Reed switch. Gems Sensors' model FS-10798 incorporates a piston which provides an alternative flow path for fluid. In the main flow path, there is a vane which can be adjusted to vary the amount of fluid flow which is required to move the piston a sufficient distance to activate the magnetic switch. The piston is equipped, of course, with a magnet, which activates an external Reed switch when it is displaced sufficiently. Therefore, there is no flow through the alternative piston path until it is displaced sufficiently to allow fluid to flow through an outlet port in the cylinder wall in which the piston moves.
It is well known to provide a dual check back-flow preventor for use in various types of systems. For example, Watts Industries, Inc., provides a Series 007 Double Check Valve Assembly. The Watts device has two moving checks in series, which are displaced by flow in a desired direction, but which positively seat to prevent flow in the undesired direction. As the checks are displaced by flow in the proper direction, flow passes out around the periphery of the checks. The checks are contained within a cage assembly, which allows passage of fluid between the legs thereof.
It is well known to provide a bypass means for allowing fluid flow around a restriction, in certain circumstances. For example, as disclosed in the Parent Applications for use in a multi-purpose piping system, it may be desirable to divert flow around a water softener where the demand for water in the residence for fire protection is greater than is able to flow through the water softener. As another example, in a chemical process, chemicals may be passed through a reactor unit. However, should the reactor become plugged or otherwise unduly restrict the flow, it may be desirable to bypass the reactor so as to prevent damage to the reactor vessel and/or a process upset. In these circumstances, it is necessary to have a bypass means which can divert flow around the flow element causing the pressure drop.
In most fluid flow systems, each of the above noted flow elements (flow measurement, check valve, bypass means) is a separate fitting which must be placed in the fluid system. It is often desirable to combine as many of the above noted functions into one device engineered for a particular purpose. The benefits of a combination of multiple devices, for example the flow meter, check valve, and means for converting a fluid flow to an electronic out put signal, are: a reduced number of devices reduces complexity, cost, and difficulty of installation of a fluid flow system.
It is also well known to provide a means for enunciating an alarm when water flows through a fire protection system. Typical commercial fire protection systems do not have significant water flow therethrough unless a sprinkler head is activated by a fire. Thus, the typical commercial system need only to detect whether or not flow is present, and if so, an alarm must be enunciated. That is why vane-type paddle flow switches are generally acceptable for commercial fire protection systems.
In U.S. Pat. No. 6,081,196, issued Jun. 27, 2000, for Apparatus And Method For Multipurpose Residential Water Flow Fire Alarm, a method was disclosed which allows the same piping to be used for both domestic and fire protection needs. The method provided for a flow detection and measurement means which is capable of distinguishing typical domestic flow from fire protection flow caused by the operation of one or more sprinkler heads. The ability to distinguish domestic flows from fire protection was based on the different flow regimes between fire protection and domestic uses.
The National Fire Protection Association (“NFPA”) has established standards for the design and operation of multi-purpose residential fire sprinkler systems. The standard is known as NFPA 13D, 1999 Ed. It defines a multi-purpose piping system (“MPS”) as “[a] piping system within dwellings and manufactured homes intended to serve both domestic and fire protection needs.”
Typical commercial fire sprinkler systems utilize a water flow detector to provide an alarm means. When a flow of sufficient, minimal, volume is detected, typical commercial systems indicate an alarm condition. The only reason that water typically flows in commercial systems is activation of a sprinkler head. Therefore, in a typical commercial system an alarm means need only determine whether or not water is flowing. Paddle flow switches are commonly used to determine when flow occurs in commercial systems. These are typically vane-type paddle flow switches.
In an MPS water regularly flows through the common piping. Flows occur to supply domestic needs within the structure. Whenever a sink, shower or toilet valve open, water flows in the MPS. Therefore, the alarm system used on typical commercial applications will not work for the MPS because simply taking a shower might cause a typical commercial flow detector to alarm when used with the MPS.
In light of this problem, typical residential and commercial applications have two completely different piping systems: (1) a fire sprinkler piping system, and (2) a domestic piping system. This doubles the number of pipes/fittings and the amount of plumbing work which has to be performed in a typical residential application. The same set of piping could not previously be used for both systems because the flow alarm could send false signals when domestic water was turned on. Alternatively, a residential application could use a fire detection system (i.e., smoke detector system). However, a smoke detection system does not alarm when water flows. Therefore, with a smoke detection system and no flow alarm, the fire sprinklers could run for days, causing extensive water damage, while the home owner is away on vacation and no alarm would sound. Also, smoke detection systems can be expensive.
As noted above, U.S. Pat. No. 6,081,196, issued Jun. 27, 2000, to Young, disclosed an Apparatus And Method For Multipurpose Residential Water Flow Fire Alarm. The apparatus for use as a multi-purpose residential fire suppression water flow alarm system disclosed in that patent was comprised of a supply side for delivering water under pressure; a multi-purpose piping system having a system side with common piping for delivering water from the supply side to a fire suppression side with one or more sprinkler heads and a domestic side for one or more domestic uses; a detecting means for detecting fire protection flow and for distinguishing that flow from a maximum domestic flow, the detecting means being disposed between the supply side and the system side; a drain test connection; and an alarm means. The method of utilizing the apparatus described above was also disclosed. One of the dependent claims from the above-noted patent, claimed a detecting means comprised of an orifice plate through which water flows causing a differential pressure measured by a differential pressure switch so that the flow rate to the orifice plate is proportional to the differential pressure allowing a determination of flow rate based on the differential pressure measured.
The flow detection means could utilize any number of well known flow measurement technologies, such as U.S. Pat. No. 5,288,469 to Otten et al. The Otten device incorporates both an orifice plate and a cone-shaped plug around which the water flows. U.S. Pat. No. 5,419,203 to Carmichael discloses a device similar to the device disclosed by Otten. Otten utilizes the Hall effect to measure the displacement of a displacement piston having a magnet incorporated therein. Carmichael utilizes strain sensors to measure the strain caused by displacement of a cone-shaped plug biased by a spring member. As the flow increases, the cone-shaped plug displaces backwardly in reaction to the flow putting greater pressure on the spring and consequently, greater pressure on the pressure sensors incorporated in the device. The Otten and Carmichael devices have several common features, namely a chamber having an orifice plate and a plug-shaped device adapted to be deflected away from the orifice plate in proportion to the flow rate through the chamber. The flow measurement means must be simple in both operation and concept so that it will be inexpensive to build and can be easily programmed and calibrated in the field. The problem with Otten and Carmichael is that their devices allow flow therethrough the instant pressure is applied across the orifice plate. As disclosed, they are not capable of serving as a bypass means for allowing flow only when the differential pressure exceeds some preset level.
Critics of the MPS have also noted that it is common for residential systems to incorporate a water softener or similar devices (such as filters, chlorination systems, UV purifiers and the like). Water softeners and similar devices can create substantial drops in system pressure and flow such that the water supply flowing through a typical residential system may not be sufficient for fire protection needs. Therefore, there is a need for a bypass mechanism which will allow sufficient flow in fire protection situations to bypass the water softener to supply the fire protection needs.
Prior art systems also suffered from problems with freezing. Where lines were in locations that could reach temperatures below freezing, it was a common problem to face freezing in the pipes, which could crack sprinkler heads and/or piping systems. Prior art systems addressed this problem in a number of ways, including dry pipe systems, which do not have any water in the piping until fire is sensed, by placing pipes in locations where they were not exposed to cold temperatures (for example, by placing insulation wrap over piping systems in favor of heated spaced below) and the like.
The NFPA allowed the MPS because, in their estimation, the cost savings associated with single systems instead of duplicate systems, would cause the MPS to be installed in more homes, thus saving more lives. However, the NFPA provides no means for alarming upon a water flow condition in the MPS, which is a system where both domestic and fire protection systems use common piping.
There was previously no flow detection means for use with an MPS. As noted above, typical flow detection means alarm upon detection of a minimum flow. Therefore, given the common piping system in an MPS, typical domestic uses could cause the prior art flow detection means to send an alarm signal to the alarm means. NFPA provided for installation of a non-water-flow-based smoke detection and alarm system for use with the MPS. These non-water-flow-based smoke detection and alarm systems are expensive, and they are not capable of detecting flow through one or more fire protection sprinklers. The inability of a smoke detection system to detect and enunciate a water flow alarm could result in extensive water damage to the property.
A cousin to the multi-purpose system for use generally in commercial applications was the “Tri-Water Systems™” that were sold by American Air Filter starting in the early 1980's. The Tri-Water System allowed for cost savings, but there was one serious flaw; namely, there was no way to provide a water alarm for the sprinkler system. Thus, the Tri-Water System was a failure. The documentation provided by American Air Filter for the Tri-Water System alleged that:                The purpose of the flow switch is to trigger an alarm when the sprinkler is activated. the flow switch manufacturers provide detailed instructions for trimming the paddles and adjusting switch spring tension. If paddles are not trimmed for actual flow conditions, nuisance alarms will be sounded; unnecessarily evacuating the building and “rolling” the fire department.Instructions provided by American Air Filter for the Tri-Water System at page 9. This statement was untrue. Manufacturers of paddle switches specifically provide that they cannot be trimmed, and must be used as they are provided by the factory. Therefore, this oversight, namely the failure to provide a flow switch, meant that very few Tri-Water Systems were installed, and the concept fell from favor. A Tri-Water System is shown in FIG. 24, with improvements incorporated pursuant to the present invention. As with the old Tri-Water System, using the present invention, the same piping to be used for heating and cooling water as well as for feeding fire protection sprinklers.        
3. Parent Applications
The Parent Applications (U.S. Pat. No. 6,081,196 issued Jun. 27, 2000, U.S. Pat. No. 6,239,708 issued May 29, 2001, and U.S. Pat. No. 6,333,695 issues Dec. 25, 2001) disclosed the MPS with a water flow alarm. Since they envisioned the MPS, common piping carried water throughout the system. After passing through the main control valve, water passed by a pressure gauge, then through a flow detection means. In combination the flow detection means and the pressure gauge allowed for determination of whether the water supply is sufficient for fire protection needs. The flow detection means was connected to an alarm means which activated upon the detection of a flow rate greater than maximum domestic flow. Methods of detecting and measuring flow and alarming upon excessive flow are illustrated, for example, in Otten, et al., U.S. Pat. No. 5,228,469. Disposed after the detection means was a drain test connection. This drain test connection served the same purpose as it did in the prior art. The drain test connection also preferably included an orifice plate with interchangeable orifice plates for simulating different flow regimes. For example, one orifice plate could simulate the operation of a single fire sprinkler while another orifice plate simulated the domestic usage. These interchangeable orifice plates could then be used to calibrate the operation of the alarm means. Common piping carried water throughout the system to both domestic and fire protection uses. Rather than having distinct fire sides and domestic sides, the Parent Applications disclosed short sections of pipe split off from the common piping which were designated as either fire side or domestic side.
The Parent Applications also disclosed a flow sensor incorporating a combination orifice flow meter/displacement magnetic flow sensor in an annular housing. The annular housing was preferably be composed of a non-magnetic, metallic material, such as aluminum. Alternatively, the annular housing could be comprised of a polymer such as CPVC or similar materials. The material of construction was not critical so long as it did not interfere with the magnetic activation of the Reed switch. The annular housing had two ends, and at each end a bushing or reducer adapted to be threadedly (or by a socket) attached thereto to allow connection of an inlet pipe at an inlet end of the annular housing and an outlet pipe at an outlet end of the annular housing. A moving orifice plate, having a front face and a back face, was adapted to be received within the annular housing. The annular housing had at least one section with a continuous diameter defined therein for receiving the moving orifice plate. The moving orifice plate had a diameter which was slightly smaller than that of the continuous diameter section of the annular housing, allowing a sliding motion therein, but preventing excess fluid to flow around a periphery of the moving orifice plate. A moving plate opening was defined at or near the center of the moving orifice plate. An orifice plate magnet flange having a diameter larger than that of the moving plate opening was disposed on a back face. Disposed substantially around and outside the flange was a circular orifice plate magnet. The moving orifice plate was biased away from the outlet end by a orifice plate spring. The orifice plate spring was contained between an interior flange shoulder near the outlet end, and the orifice plate magnet. Mounted on an exterior portion of the annular housing was a Reed switch. The Reed switch was attached to the annular housing by an adjustable attachment means. Adjustment screws held the adjustable attachment means in place and allowed it to be loosened for movement of the Reed switch for calibration of the device.
The Parent Applications also disclosed another related embodiment of the combination orifice flow meter/displacement magnetic flow sensor. This embodiment was adapted to be used in systems where a water softener or similar pressure drop causing device is present. The outlet to the water softener was on the supply side of the sensor, and the inlet from the water softener was on the system side of the sensor. A “bullet rod” was held in place by a bullet port within the annular housing. The bullet port was comprised of an outer annular ring held in place between an annular shoulder and a bushing, support legs projecting inwardly from the annular ring, and an inner support ring. An open port area was defined between each of the support legs. Preferably, the sum of the open port areas was at least as large as the cross sectional area of the inlet pipe connected to the sensor, thus, the pressure drop through the device was minimized. A bullet rod having a head portion with a leading end and a threaded male end adapted to be received through the inner support ring was provided. A tail portion had a threaded female end adapted to threadedly engage the male end, so that the tail portion is held in place against the inner support ring. The tail portion also had a tapered end. The tapered end faced the outlet end of the sensor. The moving orifice plate opening was sized to receive the tail portion so as to allow sliding motion of the moving orifice plate and also to minimize flow between the tail and the orifice plate. Thus, as the moving orifice plate was displaced toward the outlet end by pressure drop, substantially all of the flow was diverted through the water softener until the pressure drop created by fire flow displaced the orifice plate past the tapered end, at which point water flowed through the orifice in the orifice plate. As discussed below, preferably two Reed switches were provided, the first for a trouble alarm, and the second for enunciating the alarm means.
Another embodiment of a fire protection system incorporating the apparatus is discussed below. The water from the water supply first flows through a flow sensor passing through an inlet softener line to a water softener or similar water treatment or processing device and thence through the outlet softener line back through the flow sensor. The operation of the flow sensor will be more fully described hereinafter, but for the present time it is sufficient to say that the flow sensor typically directs water through the inlet softener line through the water softener and then back through the sensor to a first pipe section. However, whether there is an excessive water demand in the system, for example such as one caused by the operation of a fire protection sprinkler, there is a mechanism incorporated in the flow sensor which allows water to bypass the water softener increasing the flow rate through the system. The water, which is passed through the water softener, is next split, some of it passing into the cold water piping, and the rest of it passing into a second pipe section.
The water from the second pipe section next passes through a second flow sensor. A check valve may also be incorporated in the second pipe section. The check valve prevents back flow of water, which potentially could be stagnate from the fire protection system, to the cold water piping and/or the water softener. The second flow sensor passes water down through a water heater via an inlet heater line, and back to the sensor via an outlet heater line. Again, the second flow sensor incorporates a bypass means which allows water to bypass the water heater where there is an excessive demand. After being heated, the water passes into a multi-purpose pipe section. Attached to the multi-purpose pipe section are typical domestic uses such as a shower head and a faucet. Other uses, such as toilets, dishwashers, washing machines, and the like may also be attached to the multi-purpose pipe section. Also in communication with the multi-purpose pipe section are one or more sprinkler heads. The sprinkler heads are in communication via a passive pump and a head fitting with a multi-purpose pipe section. The operation of the passive pump in cooperation with the head fitting and the sprinkler heads will be more fully described hereinafter. However, the purpose of the passive pump is to utilize the velocity head of water flowing through the multi-purpose pipe section to circulate water to and around the sprinkler heads to minimize stagnation thereat.
Two flow sensors may be incorporated into the multi-purpose piping system. If there is no water softener, there will not be a need for one of the flow sensors. The only flow sensor will be on the hot water heater. Alternatively, it may be desirable to have only one flow sensor present at the water softener. In such a case, the flow sensor at the water softener will also measure the cold water flow, potentially contributing to more false alarms in the multi-purpose alarm system. However, this may be desirable where the risk of false alarms is not substantial, and the cost savings is sufficient enough to justify a single sensor at the water softener only. It is not believed that the hot water heater will cause a significant pressure drop in the flow therethrough. Therefore, the bypass means at the hot water heater is not believed to be necessary to ensure that adequate flow is available for fire protection needs. Rather, as shown, the advantages that the flow sensor placed on the hot water heater only measures the flow through the hot water domestic uses, as well as the flow to the fire protection sprinklers. Thus, the chance of a false alarm is minimized.
From the passive pump, water is passed to a head fitting. The water passes to the head fitting from the multi-purpose pipe section via the head supply line. It is returned to the multi-purpose pipe section via the head return line. A reverse-j fitting supplies water from the head fitting to the sprinkler head. The purpose of the reverse-j fitting is to cool the water supplied to the sprinkler head to insure that the sprinkler head is not activated by the temperature of the water supplied thereto. Most sprinkler heads are set to activate at a temperature of 155° Fahrenheit. While it is not anticipated that hot water flowing through the multi-purpose piping system will exceed that temperature (most hot water heaters have a 140° Fahrenheit maximum temperature), the reverse-j fitting helps to insure that just in case the water does exceed that temperature, the fire sprinkler is not inadvertently activated by water passing thereto.
As shown, a thermocouple in communication with the pump controller and control wiring operates to ensure that a minimum desired temperature is maintained in the common piping. The thermocouple measures the temperature of water in the common piping. If the measured temperature drops below a preselected level (preferably at least 40° Fahrenheit), the pump controller initiates the action of a pump. The measured temperature may be a water temperature in the system preferably remote from the utility room where the heater is located. Alternatively, the temperature may be an air temperature or a combination of air and water temperature measurements. The pump draws water from the common piping via a pump inlet pipe. A pump outlet pipe directs water through a check valve and a return pipe so that it is recycled through the water heater. The return pipe connects to the inlet heater line to complete the circuit. Thus, water moved by the pump through the water heater is reheated to maintain a minimum temperature in the multi-purpose pipe section.
An alternative embodiment includes a return leg supply pipe and a return leg flow sensor. The return leg supply pipe may be in communication with the first pipe section. The return leg flow sensor normally prevents any water from flowing directly from the first pipe section through the return leg supply pipe into the multi-purpose pipe section. However, when an excessive water demand is made on the multi-purpose pipe section, the pressure may drop low enough so that the return leg flow sensor (without an alarm means) allows water to pass there through directly from the first pipe section, bypassing the flow sensor and the other elements of the water heater system. Alternatively, the return leg flow sensor may draw water from the multi-purpose pipe section at a point adjacent to the outlet from the flow sensor. This creates an alternative flow path for hydraulic advantage in the design of the system.
To reiterate, one of the problems to be solved by the Parent Applications was provision of a water-flow-based means of alarming the MPS. In the past, such systems had to utilize two completely different piping systems: one for domestic uses and one for fire sprinkler system uses. Previous alarms used in these systems were designed to create an alarm condition upon the detection of a flow (commonly 8-10 gpm). As noted previously, vane-type switches are very inaccurate in determining flow rate. Typical domestic flows could have caused an alarm in a prior art system. Alternatively, prior art systems used a smoke detection and alarm system which did not have a flow detector. These systems without a flow detector risked substantial water damage to the structure if a sprinkler head activated while no one was in the home.
The Parent Applications used the principle that domestic flow rates are much lower than flow rates needed for fire protection. Using a flow detection means, it was possible to create an alarm condition only upon detection of flows which are such as created by fire protection needs. Thus, an alarm condition was not created when typical domestic uses only were detected.
Preferably, the Parent Applications also incorporated a tamper detection means on the main control valve. The tamper protection means determined whether the main control valve was closed, and if so, enunciating a trouble alarm. A pressure gauge was also preferably provided in the system.
The combination orifice flow meter/displacement magnetic flow sensor disclosed in the Parent Applications preferably had two normally open Reed switches disposed thereon for detecting flow as indicating by displacement of the moving orifice plate. The first Reed switch was the same as previously disclosed, and enunciates a fire alarm via the fire alarm means. Preferably, the first Reed switch also activated a system which contacts emergency response personnel, such as fire departments. In addition to the fire alarm Reed switch, a second Reed switch may be provided. The second Reed switch enunciated a first stage “trouble alarm”. Preferably, the first stage trouble alarm only enunciated within the structure (i.e., emergency response personnel were not contacted). The trouble alarm was created if the domestic usage was excessive. Where the system was used with the MPS, the first stage alarm would naturally cause anyone in the residence to instinctively shut off water, for example a shower they may be taking. As another example, if a resident heard a first stage alarm, and they were washing dishes, they would most likely shut off the sink faucet. This natural reaction to the first stage alarm may reduce the water flow demand below the level where the first stage alarm enunciates, eliminating the alarm condition. The first stage Reed switch is displaced a slight distance toward the inlet of the flow sensor relative to the fire alarm Reed switch. Thus, as the moving orifice plate is displaced towards the outlet end of the flow sensor, it will first activate the first stage Reed switch, enunciating the internal first stage trouble alarm. As the orifice plate continues to be displaced towards the outlet end, it will next activate the fire alarm Reed switch, which enunciates the alarm means, preferably notifying emergency response personnel. The relative linear displacement of the fire alarm Reed switch and the trouble Reed switch was to be set in the field so that there was sufficient differential in the flow which activates the first stage alarm and the fire alarm to give residents or occupants of the structures sufficient time to shut off domestic demands before a fire alarm is created. This two-stage system also serve as a safety back up, because if one of the alarm stages fail, the other still alerted residents to the potential alarm condition.
Tamper detection means on the main control valve preferably incorporated Reed switches as well. As the handle was turned, a magnet on the handle activated a normally open Reed switch, causing it to close, enunciating an alarm notifying the occupants of the structure that the main control valve had been closed, and the fire protection system was not being supplied with water. Again, this is an important safety consideration in residential systems where small children, unknowing homeowners, and the like can easily turn off the system without realizing they are shutting off their fire protection system as well. However, the tamper means is more critical in commercial stand-alone systems. Otherwise, no one might notice the valve was closed until the sprinkler system failed to operate when needed. In an MPS, the residents of the structure would quickly realize the valve was off because they would not have any water for domestic uses.
Though the Parent Applications described the inventions therein with reference to a multi-purpose piping system, it should be understood that the system could be used with any flow-based system. Further, the flow detection means disclosed herein could be used with any flow system, not just fire protection systems. That is, the flow detection means are capable of detecting the flow of any fluid through a piping system. The piping system could carry hydrocarbons, solvents, or any other liquid or potentially gaseous materials for that matter.
In operation the apparatus disclosed in the Parent Applications functioned as both a domestic water supply system and a smoke detection and alarm system. Under normal conditions, the water flow rate through the flow detection means did not reach the fire suppression flow rates. When one or more sprinkler heads activated, the flow detection means detected the increased flow and sent an alarm to the alarm means. The alarm means enunciated a visible and/or audible alarm indicating the alarm condition. It is well known in the prior art to activate a telephone modem-based system for calling, for example, the fire department, upon detection of an alarm condition. See, e.g., Otten, U.S. Pat. No. 5,139,044. It was preferable to incorporate such a modem-based component in the present invention to notify the fire department and other emergency contacts should a fire alarm condition be detected. If one or more domestic cutoff valves were included in the apparatus, the flow detection means also sent a signal to activate the domestic cutoff valves, shutting off water to one or more domestic uses and providing more water for the fire sprinklers.
When the two-stage alarm system was provided, it was necessary to calibrate both the first stage trouble alarm Reed Switch and the second stage fire alarm Reed switch. The preferred method was to first calibrate the fire alarm Reed switch. The calibration was very simple. First, the drain test connection is opened to simulate fire protection needs, the connection means for the Reed switch were loosened, and it was moved towards the inlet end of the sensor until an alarm condition was created. The first stage Reed switch was then moved a slight distance further towards the inlet end. A typical domestic demand was then created by using the drain test connection or flowing water from some number of plumbing fixtures. As the flow through the drain test connection exceeds the high end of the expected domestic demand, the first stage Reed switch should be activated, activating a first stage trouble alarm. If the alarm is not activated, the first stage Reed switch is moved further towards the inlet end of the sensor.
4. Shortcomings of the Prior Art
In prior systems it was often necessary to provide both a double check valve element and a flow detection/measurement/control sensor. Both of the elements increased the cost of this system and increased the pressure drop through the system. There was a need for a flow sensor that could both serve as a double check and as a flow detection or measurement means.
In multi-purpose piping systems, as well as stand-alone fire protection systems, there was the problem of stagnation (where water was to be used for human consumption) of water in the piping as well as the problem of freezing, where piping was exposed to temperatures lower than 32° Fahrenheit. Freezing presented itself as a problem where piping was installed, for example, in an attic of a residence. There was therefor a need for a system which provides for the warming of pipes to prevent freezing, as well as circulation through the pipes to prevent stagnation.
Another problem that plagued prior art systems was the issue of retrofitting existing structures for fire protection systems. Retrofitting for a fire protection system in a typical structure would be very expensive because, where the freezing issue is a problem, piping would have to be installed in conduits below the ceiling of the structure (or at least under insulation) to prevent the danger of freezing.
In commercial systems, fire protection sprinklers have been standard equipment for years. In addition, these buildings have also been provided with piping to circulate heated/cooled water for temperature control purposes. It would be advantageous if the fire protection piping could be combined with the piping to distribute heated/cooled water. However, the greater demands of flow required for fire protection purposes had previously prevented this dual use of the piping. The “tri-water system” which proposed to use the same piping for both purposes provided for a water flow alarm, which made the system undesirable, and eventually resulted in its abandonment.